The present invention relates to a liquid crystal display device. More specifically, it relates to a liquid crystal display device in which a slit is provided in a vicinity of a depression portion for fitting a protrusion of a housing for holding a light-conducting plate thereinto and an impact damage of a protrusion for locating of the light-conducting plate can be avoided.
FIG. 18 is an exploded perspective view for explaining structures of an illumination apparatus of a liquid crystal display device for illuminating a back surface of a liquid crystal display panel and of a housing for holding the illumination apparatus. FIG. 19 is a sectional view showing the illumination apparatus and the housing taken along the line Axe2x80x94A in a state where the illumination apparatus and the housing of FIG. 18 are assembled. A light which is emitted radially from a barshaped fluorescent lamp 8 is reflected by a reflecting plate 3 so as to be condensed onto a side surface of the light-conducting plate 1. Moreover, a rear surface of the light-conducting plate 1 is subject to an irregular reflection process (dot printing or emboss process), and a light reflecting sheet 2 is arranged thereon so as to convert the light entered the light-conducting plate 1 into a uniform plane light source and allow the light to go therefrom. Thereafter, the outgoing light is scattered or converged by various optical sheets 4 such as a diffusion plate and a lens sheet in order to secure predetermined luminance and optical uniformity, and is emitted to a back surface of a liquid crystal panel (not shown).
The illumination apparatus which is composed of the light-conducting plate 1, a light source unit 9 having the fluorescent lamp 8 covered with the reflecting plate 3, the light reflecting sheet 2 and the optical sheets 4 is held by a housing (hereinafter, referred to as a lower frame) 5 which is composed of a bottom plate 5a and a casing 5b arranged on a bottom plate peripheral area. Particularly, protrusions 1a, 1b, 4a, 4b, 6a and 6b which are protruded from a pair of side surfaces are formed on the light-conducting plate 1, the optical sheets 4 and the light reflecting sheet 2, respectively, and the protrusions 1a, 1b, 4a, 4b, 6a and 6b are fitted into depression portions 7a and 7b formed on the casing 5b of the lower frame 5 so that these members are located in a side surface direction (locating direction S).
However, in recent years, thinning and lightening of the liquid crystal display device are desired, and thus a thickness of an acrylic light-conducting plate is being reduced. As a result, it is concerned about occurrence of the following problem.
When the thickness of the light-conducting plate 1 is reduced, mechanical strength of the protrusions of the light-conducting plate 1 is weakened. Specifically, a damage such as a crack occurs on roots of the protrusions 6a and 6b due to impact to the light-conducting plate 1 in the locating direction S, and a serious situation is capable of arising.
The present invention is devised in order to solve the above problem, and it is an object of the present invention to provide a liquid crystal display device where an impact energy to protrusions of a light-conducting plate is absorbed, and even if a thinning of the light-conducting plate is improved, a damage such as a crack does not occur on roots of the protrusions.
In accordance with a first aspect of the present invention, there is provided a liquid crystal display device including a liquid crystal display panel, an illumination unit including a light-conducting plate having a protrusion protruded from a side surface of the light-conducting plate, and a housing having a bottom plate and a casing provided onto a bottom plate peripheral area for holding the light-conducting plate, wherein a depression portion into which the protrusion is fitted for locating the light-conducting plate in a direction along its side surfaces by both end surfaces is formed to the casing of the housing; an inside of the bottom plate peripheral area is processed from roots of the end surfaces along the end surfaces so that a first slit which continues to the end surfaces is formed; the casing in a position separated from the end surfaces with a predetermined interval and an inside of the bottom plate peripheral area in this position are processed so that a second slit is formed; a portion of the housing which is composed of a part of the casing sandwiched between the first slit and the second slit and the bottom plate is supported to the housing in a manner of a fixed beam with respect to a load in the locating direction.
It is preferable that the portion which is supported in the manner of the fixed beam to the housing with respect to the load in locating bidirection is provided to both ends of the depression portions.
In accordance with a second aspect of the present invention, there is also provided a liquid crystal display device including a liquid crystal display panel, an illumination unit including a light-conducting plate having at least two adjacent protrusions protruded from a side surface, and a housing having a bottom plate and a casing provided onto a bottom plate peripheral area for holding the light-conducting plate, wherein a convex-concave pattern which is composed of depression portions for fitting the protrusions thereinto and a convex rib is formed on the casing of the housing; the light-conducting plate is located in a direction along the side surface by outside end surfaces of the convex-concave pattern and inside end surfaces on both sides of the rib; an inside of the bottom plate peripheral area is processed from roots of the end surfaces along the inside end surfaces of the rib so that slits which continue to the inside end surfaces are formed respectively on both sides of the rib; and a portion of the housing composed of the rib sandwiched by the slits and the bottom plate is supported in a manner of a fixed beam to the housing with respect to a load in a locating direction.
It is preferable that the inside of the bottom plate peripheral area is processed from a root of the end surface along the outside end surface of the convex-concave pattern so that a first slit which continues to the end surface is formed, the casing in a position separated from the outside end surface of the convex-concave pattern with a predetermined interval and the bottom plate peripheral area in this position are processed so that a second slit is formed, and a portion of the housing composed of a part of the casing sandwiched between the first slit and the second slit and the bottom plate is supported in the manner of the fixed beam to the housing with respect to the load in the locating direction.
It is preferable that the portion is provided to both ends of the convex-concave pattern so as to be supported in the manner of the fixed beam to the housing with respect to the load in the locating bidirection.
In accordance with a third aspect of the present invention, there is further provided a liquid crystal display device including a liquid crystal panel, an illumination unit including a light-conducting plate having a protrusion protruded from a side surface, and a housing composed of a bottom plate and a casing provided onto a bottom plate peripheral area for holding the light-conducting plate, wherein a depression portion for fitting the protrusion thereinto is formed on the casing of the housing; the light-conducting plate is located in a direction along the side surface by both end surfaces of the depression portion; roots of the end surfaces, the bottom plate peripheral area which continues to the roots and a part of the casing which is formed by working a position separated from the end surfaces with a predetermined interval are worked into a U shape to form a U-shaped hole; and a portion which is surrounded by the U-shaped hole is supported in a manner of a cantilever to the housing with respect to a load in a locating direction.
It is preferable that the portion is provided to both ends of the depression portion so as to be supported in the manner of the cantilever to the housing with respect to the load in the locating bidirection.
In accordance with a fourth aspect of the present invention, there is still provided a liquid crystal display device including a liquid crystal display panel, an illumination unit including a light-conducting plate having at least adjacent two protrusions protruded from a side surface, and a housing having a bottom plate and a casing provided onto a bottom plate peripheral area for holding the light-conducting plate, wherein a convex-concave pattern which is composed of depression portions for fitting the protrusions thereinto and the a convex rib is formed on the casing of the housing; the light-conducting plate is located in a direction along the side surface by outside end surfaces of the convex-concave pattern and inside end surfaces of both sides of the rib; the bottom plate peripheral area is processed to surround the rib so that the U-shaped hole is formed; and the rib surrounded by the U-shaped hole is supported in a manner of a cantilever to the housing with respect to a load in a locating direction.
It is preferable that root of the outside end surfaces, the bottom plate peripheral area which continues to the roots, and a portion of the casing formed by processing a position separated from the end surfaces with a predetermined interval are processed into a U shape to form a U-shaped hole and a portion surrounded by the U-shaped hole is supported in the manner of the cantilever to the housing with respect to the load in the locating direction.
It is preferable that the portion is provided to both ends of the convex-concave pattern so as to be supported in the manner of the cantilever to the housing with respect to the load in the locating bidirection.